android-HttpURLConnection+Handler+Thread下载图片并显示

注意：

下载图片、保存图片都需要异步操作。

java代码:

package com.example.administrator.downloadimgdemo; import android.app.Activity; import android.app.ProgressDialog; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.os.Environment; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.ImageView; import android.widget.Toast; import java.io.BufferedOutputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; public class IcsTestActivity extends Activity { private final static String TAG = "IcsTestActivity"; private final static String ALBUM_PATH = Environment.getExternalStorageDirectory() + "/download_test/"; private ImageView mImageView; private Button mBtnSave; private ProgressDialog mSaveDialog = null; private Bitmap mBitmap; private String mFileName; private String mSaveMessage; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mImageView = (ImageView) findViewById(R.id.imgSource); mBtnSave = (Button) findViewById(R.id.btnSave); new Thread(connectNet).start();//获取网络图片的字节数组或者流，转换成bitmap并显示图片 // 下载图片 mBtnSave.setOnClickListener(new Button.OnClickListener() { public void onClick(View v) { mSaveDialog = ProgressDialog.show(IcsTestActivity.this, "保存图片", "图片正在保存中，请稍等...", true); new Thread(saveFileRunnable).start(); } }); } /** * 保存文件 * * @param bm * @param fileName * @throws IOException */ public void saveFile(Bitmap bm, String fileName) throws IOException { File dirFile = new File(ALBUM_PATH); if (!dirFile.exists()) { dirFile.mkdir();//创建不存在的目录 } File myCaptureFile = new File(ALBUM_PATH + fileName);//将字符串转换成抽象路径名 BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile)); bm.compress(Bitmap.CompressFormat.JPEG, 80, bos); bos.flush(); bos.close(); } private Runnable saveFileRunnable = new Runnable() { @Override public void run() { try { saveFile(mBitmap, mFileName); mSaveMessage = "图片保存成功！"; } catch (IOException e) { mSaveMessage = "图片保存失败！"; e.printStackTrace(); } messageHandler.sendMessage(messageHandler.obtainMessage()); } }; private Handler messageHandler = new Handler() { @Override public void handleMessage(Message msg) { mSaveDialog.dismiss(); Log.d(TAG, mSaveMessage); Toast.makeText(IcsTestActivity.this, mSaveMessage, Toast.LENGTH_SHORT).show(); } }; /* * 连接网络 * 由于在4.0中不允许在主线程中访问网络，所以需要在子线程中访问 */ private Runnable connectNet = new Runnable() { @Override public void run() { try { String filePath = "https://img-my.csdn.net/uploads/201402/24/1393242467_3999.jpg"; mFileName = "test.jpg"; //以下是取得图片的两种方法 方法1：取得的是byte数组, 从byte数组生成bitmap byte[] data = getImage(filePath); if (data != null) { mBitmap = BitmapFactory.decodeByteArray(data, 0, data.length);// bitmap } else { Toast.makeText(IcsTestActivity.this, "Image error!",Toast.LENGTH_LONG).show(); } //******** 方法2：取得的是InputStream，直接从InputStream生成bitmap :推荐使用***********/ mBitmap = BitmapFactory.decodeStream(getImageStream(filePath)); //********************************************************************/ // 发送消息，通知handler在主线程中更新UI connectHanlder.sendEmptyMessage(0); Log.d(TAG, "set image ..."); } catch (Exception e) { Toast.makeText(IcsTestActivity.this, "无法链接网络！", Toast.LENGTH_SHORT).show(); e.printStackTrace(); } } }; private Handler connectHanlder = new Handler() { @Override public void handleMessage(Message msg) { Log.d(TAG, "display image"); // 更新UI，显示图片 if (mBitmap != null) { mImageView.setImageBitmap(mBitmap);// display image } } }; /*---------------------------------------------获取网络图片-----------------------------------------------*/ /** * Get image from newwork * * @param path The path of image * @return byte[] * @throws Exception */ public byte[] getImage(String path) throws Exception { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setConnectTimeout(5 * 1000); conn.setRequestMethod("GET"); InputStream inStream = conn.getInputStream(); if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) { return readStream(inStream); } return null; } /** * Get image from newwork * * @param path The path of image * @return InputStream * @throws Exception */ public InputStream getImageStream(String path) throws Exception { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setConnectTimeout(5 * 1000); conn.setRequestMethod("GET"); if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) { return conn.getInputStream(); } return null; } /** * Get byte[] from stream * * @param inStream * @return byte[] * @throws Exception */ public static byte[] readStream(InputStream inStream) throws Exception { ByteArrayOutputStream outStream = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int len = 0; while ((len = inStream.read(buffer)) != -1) { outStream.write(buffer, 0, len); } outStream.close(); inStream.close(); return outStream.toByteArray(); } /*---------------------------------------------------------------------------------------------------------*/ }

布局：

<?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <Button android:id="@+id/btnSave" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="保存图片" /> <ImageView android:id="@+id/imgSource" android:layout_width="wrap_content" android:layout_height="wrap_content" android:adjustViewBounds="true" /> </LinearLayout> </ScrollView>